The present invention relates to a probe card for electrically inspecting a plurality of detection target elements, e.g., semiconductor elements on an inspection target body such as a semiconductor wafer, simultaneously.
Conventionally, when a large number of IC chips are formed on a semiconductor wafer in a semiconductor manufacturing process, whether the individual chips have initial electrical characteristics is inspected in an inspection process by using, e.g., a probe unit. If a defective component is found, this component is marked and is removed in a later process. This probe unit generally has a cassette support portion for supporting semiconductor wafers in units of cassettes, a convey mechanism for conveying semiconductor wafers one by one from the cassette support portion, a stage movable in the X, Y, Z, and .theta. directions to receive and send semiconductor wafers conveyed through this convey mechanism, and a probe card arranged above the stage. The electrical characteristics of the IC chips are inspected by bringing the probe needles of the probe card and the electrode pads of the IC chips on the semiconductor wafer into electrical contact with each other.
The probe card described above includes various types. Among them, a probe card in which probe needles are cantilevered is widely used. In a conventional probe card of this type, generally, the probe needles of the probe card are brought into electrical contact with the electrode pads of one IC chip to inspect the IC chips one by one. Recently, as the diameters of the semiconductor wafers increase, an improvement in inspection throughput is sought for. For this purpose, a probe card is developed in which upper- and lower-level probe needle groups are cantilevered by a base and different IC chips are respectively inspected simultaneously by the upper- and lower-level probe needle groups, as disclosed in, e.g., Jpn. Pat. Appln. KOKAI Publication No. 4-186855 and Jpn. UM Appln. KOKOKU Publication No. 5-48133. As an example of such a probe card, one having an arrangement as shown in FIG. 5 is known. FIG. 5 is a plan view showing the probe card from the needle side, i.e., from the lower side.
The probe card shown in FIG. 5 has upper- and lower-level first and second probe needle groups 1A and 1B and a rectangular base 2 for cantilevering these probe needle groups 1A and 1B. The needle point groups of the first and second probe needle groups 1A and 1B and all electrode pads P (see FIG. 6) of 16 (=4 rows.times.4 columns) IC chips T1 and T2 (represented by T) on a semiconductor wafer are brought into contact with each other to perform inspection of the electrical characteristics of the 16 IC chips T1 and T2 simultaneously. The base 2 is formed as a rectangular support frame having a rectangular opening portion 3 at its center. The first and second probe needle groups 1A and 1B, extending obliquely downward from the two side surfaces in the longitudinal direction of the base 2 toward the opening portion 3, are supported by the lower surface of the base 2. The first probe needle group 1A is formed short to come in contact with the outer IC chips T1, and the second probe needle group 1B is formed long to come in contact with the inner IC chips T2. The proximal portions of the first probe needle group 1A are directly fixed to the lower surface of the base 2 with, e.g., a synthetic resin, so that the first probe needle group 1A is cantilevered. The proximal portions of the second probe needle group 1B are fixed to right and left fixing plates 4, extending over the opening portion 3 in the longitudinal direction, with, e.g., a synthetic resin, so that the second probe needle group 1B is cantilevered.
In the probe card of this type, the second probe needle group 1B is cantilevered by the fixing plates 4 extending over the opening portion 3 of the base 2. Since the fixing plates 4 are thin and formed elongated, they do not have a sufficiently large mechanical strength. Then, variations occur in the needle pressure during inspection, and stable inspection cannot be performed accordingly. Since the fixing plates 4 tend to flex, when mounting the second probe needle group 1B on the fixing plates 4, the fixing plates 4 flex to degrade the precision of the needle positions. Also, since variations occur in the height of the needle points, it is technically difficult to align the needle points. Therefore, to mount the second probe needle group 1B on the fixing plates 4 requires a skill.